1. Field of the Invention
The present invention relates to nanometer-sized crystallites or quantum dots having semiconductor properties, and more particularly to an improved process for synthesizing such crystallites from readily available, inexpensive starting materials and under mild reaction conditions.
2. State of the Art
The synthesis of metal chalcogenide quantum dots, such as of zinc selenide, is known but the existing methods are unsatisfactory and not amenable to scale-up. For example, Murray et al disclose a method for the synthesis of cadmium selenide quantum dots in the Journal of the American Chemical Society, Vol. 115, pages 8706-8715 (1993). This method makes use of tri-n-octylphosphine as a coordinating solvent, either elemental selenium or bis(trimethylsilyl)selenium as the chalcogenide donor, and dimethylcadmium as the metal donor. The disadvantage to this method is the nature of the reactants, most of which need to be synthesized, and the use of an expensive, air sensitive, unstable, solvent as well as the need for high reaction temperatures. This method is considered to be unsatisfactory for the production zinc selenide.
There exists a need for a process for producing metal chalcogenide nanocrystals or quantum dots from readily available, stable reactants and mild reaction conditions which process can be carried out on a relatively large scale economically and efficiently.